In general, plumbing installation involves two stages. The first stage is the “rough plumbing installation.” This stage generally occurs after a structure has been framed out and before walls for the structure are closed with drywall. The second stage is the “finish plumbing installation.” This stage generally occurs after cabinets, drywall, sinks, counters, etc. have been installed at the structure. In between the two stages, other workers may hang drywall, mud the drywall, install tile and flooring, and install fixtures.
For many years, and until very recently, most plumbers would make their transition between the rough plumbing installation and the finish plumbing installation by “stubbing out” with copper pipe and closing the copper pipe with a metal nipple. At the finish plumbing installation, the plumber cuts off the nipple and sweats on a valve.
Currently, with the advance of flexible piping, such as PEX pipe, plumbers are stubbing out with the flexible pipe during the rough plumbing installation. After stubbing out with the flexible pipe, the plumbers crimp a test cap on to the end of the flexible pipe stub out with a crimp ring. This may complete the rough plumbing installation. The plumbers then return at a later date to perform the finish plumbing installation and complete the job. During the finish plumbing installation, the plumbers cut off the test cap and the crimp ring from the flexible pipe stub out, and then may crimp on a valve suitable for the flexible pipe. This practice has numerous problems. First, the stub out is often fouled with paint or other debris, such as drywall mud. Second, the stub out is often scarred from job-site abuse. This makes a push connection or a crimping connection to the stub out difficult and may result in improper sealing of the valve to the stub out.
Conventional flexible pipe connections can also be difficult to properly make. Specialized tools are required at the finish plumbing installation in order to both cut the pipe and to crimp on the final valve to the pipe. This can also be very difficult, as the finish plumbing installations are often in tight spaces, such as behind a toilet or under a counter and sink.
Further, after the flexible pipe has been cut and the valve crimped thereon, it makes the valve very hard to service or replace in the future. This is because there is often little to no flexible pipe left before the valve. And, if the valve needs to be cut out or fixed, the plumber may have to tear out the drywall, which is expensive and difficult. Further, the final assembly of the valve is time consuming and wasteful, as the test cap and ring are thrown away and the plumber must make a difficult connection, with the appropriate tool, often in awkward positions.